There has been conventionally known a ball-point pen, in which an ink tank in which an ink for a ball-point pen is accommodated is disposed in a shaft cylinder, and a ball is put on the bottom wall of a ball holding portion, and which includes a pen point of which the leading end portion is inwardly crimped, whereby a part of the ball is allowed to protrude from the leading edge of the pen point, and the ball is rotatably held.
A ball-point pen performs writing by transferring ink, flowing out of an ink tank, onto a body to be recorded, such as paper, or by allowing the ink to infiltrate into the body to be recorded, due to rotation of a ball. The wear of the ball and the inner surface of a ball holding portion prevents the ball from smoothly rotating, results in great deterioration of writing characteristics, and finally precludes writing. Therefore, the reduction of the wear of the ball and the ball holding portion is an important problem.
Use of a ceramic ball, coating of the surface of a metallic ball with a rigid material such as a diamond-like carbon film for reducing the wear of the ball and the ball holding portion (for example, Patent Literature 1), and the like have been attempted with respect to such problems. Coating of the surface of not only the ball but also the ball holding portion with a rigid material for reducing the wear of the ball holding portion by the ball has been also attempted.